Two types of herpes
As a general rule, herpes simplex is herpes simplex. Usually, type 1 causes
oral, lip, and facial herpes, while type 2 causes genital herpes. However,
type 1 may cause genital herpes and type 2 may cause oral herpes. In general,
however, in North America, over 90% of recurrent genital herpes is caused
by type 2. This continues to be true because type 2 herpes simplex virus infection
recurs much more efficiently on the genital area compared with type 1. In part,
this is probably due to the efficiency of type 2 herpes in attaching itself
to nerve cells (neurons) in the sacral ganglia.
By contrast, primary genital infection from a type 1 infection is very common.
Primary infection results from external inoculation of skin cells from the infected
skin of another. Latent infection takes place as a result. The opposite situation
takes place with recurrent infection, where sores result from reactivation of
latent neuron infection in the same person. In fact, nearly half of true
primary genital herpes is now caused by type 1. Type 1 genital primaries
are on the rise for a number of reasons. First of all, primary infection depends
on how much virus is present in the skin of the source partner during contact.
Type 1 contact potential may be increasing in adulthood because oral sex is
becoming more common and is rarely a protected sexual practice (using latex
barriers, for example). The vast majority of type 1 genital herpes results from
unprotected oral-genital sex.
Even more importantly, the level of our immunity to type 1 oral-labial herpes
in adults is now much lower than it ever was. This is, of course, all the
fault of our parents! They were much more aware of and careful with their cold
sores than previous generations were. Their careful hygiene markedly reduced
the incidence of facial type 1 herpes in children. However, these precautions
have also had the side effect of leaving us significantly more susceptible to
both type 1 and type 2 herpes simplex virus transmission as adults.
Therapy is now available for treatment of herpes infections. Some of the therapy
being developed may be type-specific. Some laboratories now do herpes typing
routinely.
It's important to know which type of herpes you have
The virus should be
typed accurately during the very first episode of genital herpes. Type 1 and
type 2 have very different outcomes regarding recurrence frequency and very
different habits regarding methods of transmission. These differences can be
quite important. For example, if a first genital outbreak occurs in a young
child, the possibility of sexual abuse should be investigated by the authorities.
If the child has type 1 genital herpes, it becomes possible or perhaps likely,
that he or she acquired herpes through nonsexual contact. But while it is possible
to conceive of a nonsexual mode of transmission for type 2 genital herpes to
a child, those situations must be rare.
It is also important to know your herpes type because most primary outbreaks
caused by type 1 will not lead to frequent recurrences. Type 1 recurrent
herpes generally occurs far less often than type 2.
Another reason to find out which type you have is that if it is type 1, it
was probably transmitted through oral-genital contact; if so, it is likely that
your sexual partner got herpes in a nonsexual way, because most type 1 herpes
is transmitted through mouth/facial contact in childhood. Type 1 genital herpes
is also less frequently shed without symptoms compared with type 2. If transferred
during childbirth to cause neonatal herpes, type 1 can cause serious infections
for the newborn, but is less likely to lead to long-term problems in the infant
following recovery. On the other hand, since recurrent herpes has already established
its pattern, typing is often of little clinical consequence in this setting.
Frequent genital herpes recurrences are almost always caused by type 2. If
your current or future partner ever wishes to use the Western blot (blood) test
for herpes, knowledge of the typing of your virus isolate will be very useful
in interpreting the meaning of the result in your relationship.